I have created an new functionality that you might like. I needed an user interface to add the link post meta for my users. This is what I came up with. View a screenshot (Dutch!).
The text says:

The following URL makes the full slide clickable.Enter the URL manually or select a page below. Leave the field empty to disable the link.
Selecting a page will overwrite the manually entered URL when post is updated.

Users can type the URL themselves, or select a page from the drop down.